Two-section air duct

ABSTRACT

The invention relates to an air duct  1  for motor vehicles, having a two-section duct wall  3  which is formed by a covering element  4  used at least partially as the first duct wall section  3.1  and by a car body element used as the second duct wall section  3.2

BACKGROUND AND SUMMARY OF THE INVENTION

This invention relates to an air duct for motor vehicles having a flowlongitudinal axis and at least one duct wall, at least partiallyencasing the flow longitudinal axis in the circumferential direction.

German document DE 1430918 discloses a ventilation device for vehicles,in particular motor vehicles, with ventilation openings, which arearranged in the windows or door frames, which are of at least partiallyhollow design, and which connect the interior of the vehicle to theoutside air. The air flowing through the interior of the vehicle entersthe cavity through the openings during the journey, flows upward withinthe door frame on both sides and exits again from the cavity throughopenings.

It is known from German document DE 195 21 192 A1 that outgoing airflows out of the interior of the passenger cell in the region of thewindows through the side walls behind the ceiling covering and fromthere through apertures into the further ducts of the roof closingpanel, which ducts are used for guiding outgoing air. The air istherefore guided, on the one hand, by covering parts and, on the otherhand, by ducts provided for this purpose.

One object of the present invention is the object of designing andarranging an air duct in such a manner that a simple, partiallyoptimized construction and a noise-optimized use are ensured.

This object is achieved according to the invention by way of a duct wallwhich has a first duct wall section and at least one second duct wallsection, and by having the first duct wall section at least partiallyformed by a covering element and the second duct wall section at leastpartially formed by a car body element.

The effect achieved by this is that resolution of the conflict betweenthe aims of a functioning ventilation of the vehicle interior, theacoustics of the vehicle interior and the use of components which, asfar as possible, are multifunctional and lightweight is ensured. Theintegration of the air duct into the interior covering makes it possibleto avoid additional sections for the duct. In addition, the coveringparts and their properties can be at least partially used in order tooptimize the development of noise in the passenger interior.

For this purpose, it is advantageous for the first duct wall section tobe able to be placed against the second duct wall section in aconnectable and sealing manner in the circumferential direction withrespect to the flow longitudinal axis. Both duct wall sections surroundthe flow longitudinal axis or the flow main axis and therefore form anair duct which is closed around the flow longitudinal axis. Thecross-sectional shape of the air duct may be designed here as desired.Provision is also made for the cross section to change with respect tothe flow longitudinal axis or flow direction. An optimum transportationof air is therefore firstly ensured, and secondly a development of noisecoming from the air duct into the passenger interior is prevented.

According to one development, an additional possibility is for theinside in each case of the first duct wall section and/or of the secondduct wall section to have at least one acoustically active layer. Theuse of an acoustically active layer optimizes or reduces the input ofsound emanating from the air duct into the passenger interior.

Furthermore, it is advantageous for the inside of the first duct wallsection and/or of the second duct wall section to have a firstacoustically active layer and at least one second acoustically activelayer which is superimposed or arranged on the first acoustically activelayer. The use of a plurality of acoustically active layers which arearranged one above another ensures an optimum coordination of theacoustic insulation.

It is also advantageous for the first acoustically active layer to havea larger volume weight than the second acoustically active layer, andfor the first acoustically active layer to be designed as a high-passfilter with respect to the noise frequency and for the secondacoustically active layer to be designed as a low-pass filter. The useof different volume weights for the acoustically active layers makes itpossible for account to be taken of the frequency band which isgenerated in the air duct and transmitted by the air duct. Theacoustically active layer with the greater volume weight, i.e. with thegreater density, will prevent medium and low frequencies from beingirradiated acoustically from the air duct into the passenger interior.It is used as a high-pass filter. Corresponding to this, the use ofacoustically active layers with a low volume weight, i.e. with lowdensity, leads to the absorption of high-frequency components of theacoustic stream to be absorbed. They are therefore used as low-passfilters.

According to one preferred embodiment of the invention, provision isfinally made for a sealing element to be provided between the first ductwall section and the second duct wall section. The use of an additionalsealing element ensures that the air duct is soundproof.

In conjunction with the design and arrangement according to theinvention, it is advantageous that at least one releasable connectingelement is provided between the first duct wall section and the secondduct wall section. The releasable connecting elements are used for thesimple and rapid installation and the correspondingly simple and rapidremoval of the covering elements or of the duct wall sections.

It is furthermore advantageous for the first duct wall section to havetwo sides which can be placed with their end faces onto the second ductwall section. The flow longitudinal axis is therefore entirelysurrounded by the air duct in the circumferential direction.

In addition, it is advantageous for the first duct wall section to be ofL- or U-shaped design in cross section, and for sides thereof to run,with respect to the flow cross section, approximately parallel to thesecond duct wall to form two limbs of the profile.

Further advantages and details of the invention are apparent from thepatent claims, explained in the description, and illustrated in thefigures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a sectional illustration of the air duct with first andsecond duct wall sections; and

FIG. 2 shows a perspective view of a covering element with two duct wallsections.

DETAILED DESCRIPTION OF THE INVENTION

The air duct 1 which is illustrated in FIG. 1 is formed from a firstduct wall section 3.1 and a second duct wall section 3.2. The secondduct wall section 3.2 is here part of a car body element 5 or of the carbody wall and is L-shaped in cross section.

The first duct wall section 3.1 is likewise L-shaped in cross sectionwith a first limb 3.3 and a second limb 3.3′. The two limbs 3.3, 3.3′bear in this case with their end faces against the second duct wallsection 3.2 and against the car body element 5.

The first duct wall section 3.1 is formed from a covering element 4which has a first acoustically active layer 6.1 on the inside of the airduct 1, and a second acoustically active layer 6.2 above it. The twoacoustically active layers 6.1, 6.2 arranged one above the other arelikewise of L-shaped design in cross section in accordance with the Lshape of the covering element 4. And they butt with their respective endfaces against the car body element 5.

The first acoustically active layer 6.1 is of substantially thinnerdesign here than the second acoustically active layer 6.2 and also has agreater density than the second acoustically active layer 6.2.

At the end of the second limb 3.3′, the covering element 4 has a closingelement 3.4 which permits the point of abutment between the coveringelement 4 and the car body element 5 to taper at an acute angle.

The covering element 4 which is illustrated in FIG. 2 has two duct wallsections 3.1, 3.1′ and is arranged in a motor vehicle back (notillustrated specifically). The respective duct wall sections 3.1, 3.1′are assigned an inlet flow 2.2′ which is deflected toward the motorvehicle rear and leaves the vehicle rear as an outlet flow 7, 7′. Therespective duct wall sections 3.1, 3.1′ are equipped here, according toFIG. 1, with a first acoustically active layer 6.1 and a secondacoustically active layer 6.2 on the inside of the covering element 4.

1-10. (canceled)
 11. A duct wall of an air duct for motor vehicleshaving a flow longitudinal axis, the duct wall at least partiallyencasing the flow longitudinal axis in the circumferential direction andcomprising: a first duct wall section, and at least one second duct wallsection, wherein the first duct wall section is at least partiallyformed by a covering element, and wherein the second duct wall sectionis at least partially formed by a car body element.
 12. The duct wall asclaimed in claim 11, wherein the first duct wall section can be placedagainst the second duct wall section in a connectable and sealing mannerin the circumferential direction with respect to the flow longitudinalaxis.
 13. The air duct wall as claimed in claim 11, wherein an inside ofthe first duct wall section has, an inside of the second duct wallsection has, or insides of the first and second duct wall sections haveat least one acoustically active layer.
 14. The air duct wall as claimedin claim 11, wherein an inside of the first duct wall section has, aninside of the second duct wall section has, or insides of the first andsecond duct wall sections have a first acoustically active layer and atleast one second acoustically active layer which is superimposed orarranged on the first acoustically active layer.
 15. The air duct wallas claimed in claim 14, wherein the first acoustically active layer hasa greater volume weight than the second acoustically active layer. 16.The air duct wall as claimed in claim 14, wherein the first acousticallyactive layer is designed as a high-pass filter with respect to noisefrequency and the second acoustically active layer is designed as alow-pass filter.
 17. The air duct wall as claimed in claim 11, wherein asealing element is provided between the first duct wall section and thesecond duct wall section.
 18. The air duct wall as claimed in claim 11,wherein at least one releasable connecting element is provided betweenthe first duct wall section and the second duct wall section.
 19. Theair duct wall as claimed in claim 11, wherein the first duct wallsection has two sides which can be placed with their end faces onto thesecond duct wall section.
 20. The air duct wall as claimed in claim 11,wherein the first duct wall section is of L- or U-shaped design in crosssection, and wherein sides thereof run, with respect to a flow crosssection, approximately parallel to the second duct wall part to form twolimbs of a profile.
 21. The air duct wall as claimed in claim 12,wherein an inside of the first duct wall section has, an inside of thesecond duct wall section has, or insides of the first and second ductwall sections have at least one acoustically active layer.
 22. The airduct wall as claimed in claim 12, wherein an inside of the first ductwall section has, an inside of the second duct wall section has, orinsides of the first and second duct wall sections have a firstacoustically active layer and at least one second acoustically activelayer which is superimposed or is arranged on the first acousticallyactive layer.
 23. The air duct wall as claimed in claim 22, wherein thefirst acoustically active layer has a greater volume weight than thesecond acoustically active layer.
 24. The air duct wall as claimed inclaim 22, wherein the first acoustically active layer is designed as ahigh-pass filter with respect to noise frequency and the secondacoustically active layer is designed as a low-pass filter.
 25. The airduct wall as claimed in claim 12, wherein a sealing element is providedbetween the first duct wall section and the second duct wall section.26. The air duct wall as claimed in claim 12, wherein at least onereleasable connecting element is provided between the first duct wallsection and the second duct wall section.
 27. The air duct wall asclaimed in claim 12, wherein the first duct wall section has two sideswhich can be placed with their end faces onto the second duct wallsection.
 28. The air duct wall as claimed in claim 12, wherein the firstduct wall section is of L- or U-shaped design in cross section, andwherein sides thereof run, with respect to a flow cross section,approximately parallel to the second duct wall part to form two limbs ofa profile.
 29. The air duct wall as claimed in claim 13, wherein asealing element is provided between the first duct wall section and thesecond duct wall section.
 30. The air duct wall as claimed in claim 13,wherein at least one releasable connecting element is provided betweenthe first duct wall section and the second duct wall section.